tools lib traceevent: Handle INVALID_ARG_TYPE errno in pevent_strerror

gcc on f14 32-bit rightly complains:

   tools/lib/traceevent/event-parse.c:5097:2: error: enumeration value ‘PEVENT_ERRNO__INVALID_ARG_TYPE’ not handled in switch

The entry for it is in the error strings array pevent_error_str[]:

        _PE(INVALID_ARG_TYPE,   "invalid argument type")

It was just not being handled on the pevent_strerror switch, fix it.

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/n/tip-c68zkvxw4289uqbosfkz963g@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>